BOSTON, MASSACHUSETTS — A concealed carrier happened upon a man who had just broken into a vehicle and was trying to steal some items that he wanted for himself. Instead of getting a job and paying for things like a respectable citizen, this man decided to be a thief instead.

The tense episode unfolded at 5:34 a.m., when Boston police were called to the area of West Sixth and F for a person breaking into a vehicle, said Sergeant Detective John Boyle, a department spokesman. While the officers were en route, Boyle said, another call came in for shots fired.

Boyle said a witness at the scene told police that he heard the sound of glass breaking and then saw a man removing a computer case from a parked vehicle. That witness came outside and chased the suspect, who fled on foot.

During the chase, the suspect apparently turned around and brandished a knife. The armed citizen’s reaction was to fire a single shot. No one was hit by the shot, but it was enough to send the knife-wielding man running even faster.